Fiber optic systems are now commonly used for transmitting optical communication signals, i.e., optical signals modulated to encode desired information. The optical communication signals are transmitted across a network using optical fibers that support substantial transmission capacity with compact fiber bundles. Given the ever-increasing demands for improved signal quality and bandwidth, it is anticipated that use of fiber optic communications will continue to increase for years to come.
One of the reasons that fiber optic networks have attracted attention in recent years relates to switching advantages. Because the communication signals in fiber optic networks are optical in nature, conventional electronic switching components can be eliminated. Instead, fiber optic communications lines are connected at a switch by carefully aligning the fiber ends of the lines to be connected for direct optical linkage. Such switching has proved advantageous in that switching can be accomplished quickly.
Between the switches, various lengths of fiber optic line carry the optical signals. The lengths of fiber optic line are connected together using splices or connectors. The lengths of fiber optic line may also include cascaded chains of optical amplifiers which act to amplify the signals in order to maintain signal strength.
In order to increase the amount of information being transmitted across a fiber optic telecommunications network, wavelength division multiplexing (WDM) has been employed. In a WDM system, each individual fiber carries signals at a number of different wavelengths. At a predetermined point in the system, the optical signal is demultiplexed and the individual signals are transmitted to unique destinations.